This application is based on Japanese Patent Application No. 2006-180139 filed on Jun. 29, 2006, the contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a large-capacity paper storage device which stores paper and also which feeds the paper to an image forming apparatus, such as a copier, a printer, a facsimile, or the like. The invention more specifically relates to a method of reliably positioning at a predetermined position a width regulating member which regulates a side end of paper regardless of a paper size.
2. Description of Related Art
For example, sharing of one image forming apparatus by a large number of users increases paper consumption per image forming apparatus. Thus, an image forming apparatus has been in development which is loaded with a large-capacity paper storage device capable of storing a larger number of paper. In such a large-capacity paper storage device, paper is resupplied by the thousands. Thus, upon paper resupply, the user resupplies the paper into a paper storage cassette (paper storage section) a plurality of times.
FIG. 7 is a plan view of a conventional large-capacity paper storage device. FIG. 8 is a side sectional view of the paper storage device (cross section taken along line AA′ of FIG. 7). The paper storage device 100 is of a large-capacity type capable of storing paper by the thousands, in which paper is resupplied from above a paper storage cassette 1. Numeral 2 denotes an elevating plate which is vertically elevatable in the paper storage cassette 1. The elevating plate 2 is driven by an elevator (not shown) composed of wires, a take-up pulley, and the like. The paper storage device 100 is coupled to an image forming apparatus (not shown) adjacent thereto on the left of FIG. 8. Once image formation is started, paper 3 inside the paper storage cassette 1 is sequentially fed into the image forming apparatus through the paper feed section 4. The timing of feeding the paper 3 by the paper feed section 4 is controlled by a control signal transmitted from a control section on the image forming apparatus side.
On the bottom surface 1a of the paper storage cassette 1, a pair of width regulating members 5a and 5b for positioning paper in the width direction and a posterior end regulating member 6 for aligning the posterior ends of paper are vertically provided in such a manner as to penetrate through holes 2a, 2b, and 2c formed in the elevating plate 2. In the elevating plate 2, in addition to the through holes 2a to 2c, a plurality of through holes or notched parts (not shown) are provided. Any of the through holes or the notched parts can be selected and the width regulating members 5a and 5b and the posterior end regulating member 6 can be arranged at positions in accordance with a predetermined paper size to thereby store paper of the predetermined size at a predetermined position in the paper storage cassette 1.
A conventional large-capacity paper feed cassette is typically configured, as described above, to be capable of adjusting in a stepwise manner the positions of the width regulating members 5a and 5b in accordance with so called regular paper sizes, such as A4, B4, and the like. Or, the conventional large-capacity paper feed cassette is configured, as disclosed in patent documents 1 and 2, to be capable of free adjustment in accordance with various paper sizes not limited to the regular sizes.
On a paper feed cassette that performs paper feeding with respect to the widthwise center of paper as a reference (center reference), when two types of paper, for example, paper in an A4-size (with a width of 210 mm) and paper in a letter size R (with a width of 8.5 inches=216 mm) are loaded, a difference in the distance from the center reference to the paper side end between the two types of paper is only 3 mm, and thus their left and right width regulating members need to be adjusted by shifting of 3 mm.
Now, for example, to perform positioning with the upper ends of the width regulating members 5a and 5b being bent horizontally and with a positioning hole on the width regulating member side brought into engagement with a positioning projection on the cassette body side, the positioning projections respectively corresponding to the A4 size and the letter size need to be located in extreme proximity (at an interval of 3 mm), which possibly results in adjustment to a wrong position with respect to the paper size. Moreover, to avoid, upon engagement of the positioning hole with one of the projections, interference with another one of the projections, fitting sections of the width regulating members need to be configured in a complicated manner.
A possible method of avoiding the problems as described above is to provide two positioning members which have positioning projections respectively corresponding to a metric paper size and an inch-based paper size provided separately from each other and then selectively use them in accordance with the paper size. However, this method leads to an increase in the number of components.
Further, a too narrow width of the width regulating member for the paper width results in load which causes paper jam upon paper transport. On the other hand, a too broad width of the width regulating member for the paper width results in paper misalignment in the width direction, thus causing paper skew. However, even commercially available paper of a regular size has some size variation. Thus, the configuration such that the width regulating member is finely adjusted in a stepwise manner in accordance with paper of a regular size fails to finely adjust the width of the width regulating member in accordance with paper size variation. Even the configuration as in patent documents 1 and 2 such that adjustment can be freely made in accordance with a paper size provides no reference for adjustment upon positioning the width regulating member, thus resulting in difficulty in delicate position adjustment.
On the other hand, patent document 3 discloses a paper feed cassette in which a positioning member for regulating members can be switched accordingly between an inch-based paper size and a metric paper size. However, the method disclosed by the patent document 3 is based on the assumption that the regulating members are used for a paper feed cassette of a type in which the regulating members slide along the cassette bottom surface. Thus, this method is hard to apply to positioning of a width regulating member which is used in the large-capacity paper storage device 100 as described in FIG. 8, which is long in the paper loading direction, and which is engaged and fixed with the cassette body.
[Patent Document 1]JP-A-S63-208438[Patent Document 2]JP-A-2004-123396[Patent Document 3]JP-A-2005-126150